The present invention relates to an attachment for microscope tubes which serves for the correction of ametropia of the user of the microscope.
If an observer with ametropia, i.e., defective eyesight, wishes to use a binocular microscope, for instance an operation microscope, he must take special measures or use auxiliary devices in order to obtain a sharp, high-contrast image.
That is, if the person normally wears eyeglasses and tries to use the microscope without wearing such eyeglasses, the measures to be taken may consist of displacement of the microscope in an axial direction, or the shifting of the eyepiece lenses. However, such measures can not compensate for astigmatic visual defects. Moreover, displacing the microscope in an axial direction in order to correct for ametropia can be successful only if both eyes of the user have the same visual deficiency and if simultaneous observation through the microscope by other persons is not intended.
On the other hand, if persons who need eyeglasses try to wear them when using a binocular instrument, they have difficulty getting their eyes close to the eyepiece tubes, and they are troubled by stray light if they cannot accommodate their eyeglass frames to the rubber cups at the viewing ends of the tubes. Also, to permit observers to wear their own eyeglasses, the eyepiece must be so designed that the exit pupil can be brought into the pupil of the eye of the observer. The disadvantage of this solution is that there are different spectacle-frame constructions which may have different distances between the corneal vertex and the eyeglass lenses, so that the required position of the pupil is not obtained and the visual fields may be trimmed in disturbing fashion.